ANET A8 optical z probe (BLtouch like with servo)

My big inductive probe suddenly died (led always ON) after only 6 months of good services... I ordered a new one on ebay from China, but as I woudd have to wait 4 weeks or so I decided to build an optical one which to my big surprize seems being really very accurate.

The idea is to make it as minimal as possible with just a flag attached to a metal pin moving between the fork of an optical IR sensor. The design makes the pin fully free to move under gravity and a cheap RC servo motor will pa